The patent application (Publication No.: CN102335903A) discloses a labor-saving stapler, which is added with an auxiliary upper cover and realizes labor-saving operation with a double-lever principle. However, because the lower end of the auxiliary upper cover is hinged at the front end of a base and the upper end of the auxiliary upper cover is slidably connected into a first slide slot of an upper cover through a first transmission pin, in such case, the lower end of the auxiliary upper cover cannot move while a second transmission pin on a staple-pressing plate is located at a position close to the front end of the staple-pressing plate, thereby the upper end of the auxiliary upper cover and the first slide slot are located approximately the middle position of the upper cover, as a result, as the upper cover is pressed down, the resisting arm of the upper cover is long, and consequently, an optimal labor-saving effect cannot be achieved; and moreover, the opening angle of the upper cover is small, so it is inconvenient to put staples into a staple pin track.
A staple-mounting mechanism of an existing stapler comprises an upper blade holder, an external staple pin track, an internal staple pin track, a staple pusher, a staple pusher spring, and a long pin; the long pin is arranged in the external staple pin track, and is fixed at both ends of the external staple pin track; the staple pusher sleeves the long pin, and is arranged in the external staple pin track; the rear end of the staple pusher is connected to the front end of the staple pusher spring, the rear end of the staple pusher spring is connected to the rear end of the staple pin track; staples are mounted between the front end of the staple pusher and the front end of the external staple pin track, the staple pusher in the staple pin track is limited and pushed by the spring at the rear end of the staple pusher, and the staples can be pushed out by the staple pusher. Therefore, the quantity of the mounted staples between the front end of the staple pusher and the front end of the staple pin track is limited by the position of the staple pusher. Since the staple pusher spring can produce elastic force when compressed, a user has to open an upper blade and press the staple pusher with one hand in order to successfully mount the staples with the other hand when mounting the staples, and therefore, not only is it inconvenient to mount the staples, but also the quantity of the mounted staples is reduced due to the affection of the resilience force of the spring on the staple pusher.